. >> reporter: by one count, president obama has already used unmanned cia drones to strike more than 300 suspected terrorist targets, even more than his predecessor. but today, we learned just how much authority the administration believes it has to kill, without trial or evidence, suspected terrorists, even american citizens. a newly disclosed justice department document says american citizens tied to al qaeda can be killed, if, "an informed, high-level official believes the target poses an imminent threat." but the document says it "does not require the government to have clear evidence." case in point, anwar al awlaki, an american citizen and top al qaeda leader, linked to several terrorist attacks. he was killed in a 2011 drone strike. human rights advocates say the justice department memo goes way too far. and -- >> justifies essentially a claim that the executive branch can be judge, jury and executioner. >> reporter: as soon as he became president, barack obama stopped cia tactics like waterboarding that he considered torture. but this justifies outright killing of a suspected